Human activities pressure the socio-ecological system that maintains our quality of life by causing global repercussions such as climate change. The energy system, a major contributor to climate change due to its reliance on fossil fuels makes the transition to sustainable energy an imperative. The purpose of this thesis is to identify focus areas that support businesses in changing their energy habits. This leads to the research question: How can local businesses on small islands become drivers in the transition towards sustainable energy? The Framework for Strategic Sustainable Development (FSSD) enabled us to employ a systems perspective, place sustainable energy into a comprehensive and scientific definition of sustainability, and align our findings’ relevance to a strategic approach. The Motivation-capability-implementation- results (MCIR) framework was a suitable tool for our needs. For data collection purposes, literature analysis and a case study on the French island Île d’Oléron were conducted. The main findings of the thesis are that in order for businesses to become drivers in the transition to sustainability energy, Awareness, Consistent and Proactive Political System, Engaged Community, Supporting Infrastructure, Financial Capability and Agile Approach need to be addressed. The six focus areas cover the many barriers and enablers for achieving sustainable energy.

Britain and Germany are two countries that are internationally recognised for their energy efficiency policies in the area of domestic buildings. Although pursuing similar objectives, the two countries have quite different flagship policies: Germany put in place a large loan and grant scheme to finance residential energy efficiency measures in 2001, the CO2-Building Rehabilitation Programme. The UK was the first country in Europe that introduced Energy savings obligations in 1994. Since then the policy instruments in both countries experienced significant change. This thesis explores the politics of the changes that occurred, and investigates the policy processes that led to the modifications. Mainstream theories of policy change emphasise short-term crisis-like events when it comes to explaining why policies change significantly. However, more recent theoretical approaches suggest that gradual mechanisms, including accumulating external pressures and slowly developing consequences of the policies themselves, play an important role as well. In order to approach the two cases theoretically, this thesis draws on the concept of friction developed in Punctuated Equilibrium Theory and the policy feedback literature. This thesis investigates how long-term pressures, for example the perceived impact of climate change and rising energy prices, affected the evolution of the key home energy efficiency policies in Britain and Germany. Combined with assessing the impact of institutional changes and policy feedback, a comprehensive analysis of long-term policy change is carried out. A set of different methods is employed to undertake the investigation including qualitative and quantitative research methods such as semi-structured interviews with more than 25 experts followed by qualitative content analysis, complementary document analysis, and the review of data sets. The analysis provides a detailed historical case study of the key home energy efficiency policy instruments in Germany and the UK with a focus on the causal mechanisms of gradual pressures. Wider conclusions are drawn for the theories of policy change and how gradual pressures might be accounted for in those theories in a more meaningful way.

Organizations are turning to private clouds due to concerns about security, privacy and administrative control. They are attracted by the flexibility and other advantages of cloud computing but are wary of breaking decades-old institutional practices and procedures. Private Clouds can help to alleviate these concerns by retaining security policies, in-organization ownership and providing increased accountability when compared with public services. This work investigates how it may be possible to develop an energy-aware private cloud system able to adapt workload allocation strategies so that overall energy consumption is reduced without loss of performance or dependability. Current literature focuses on consolidation as a method for improving the energy-efficiency of cloud systems, but if consolidation is undesirable due to the performance penalties, dependability or latency then another approach is required. Given a private cloud in which the machines are constant, with no machines being powered down in response to changing workloads, and a set of virtual machines to run, each with different characteristics and profiles, it is possible to mix the virtual machine placement to reduce energy consumption or improve performance of the VMs. Through a series of experiments this work demonstrates that workload mixes can have an effect on energy consumption and the performance of applications running inside virtual machines. These experiments took the form of measuring the performance and energy usage of applications running inside virtual machines. The arrangement of these virtual machines on their hosts was varied to determine the effect of different workload mixes. The insights from these experiments have been used to create a proof-of- concept custom VM Allocator system for the OpenStack private cloud computing platform. Using CloudMonitor, a lightweight monitoring application to gather data on system performance and energy consumption, the implementation uses a holistic view of the private cloud state to inform workload placement decisions.

This thesis is concerned with the energy efficiency of cellular networks. It studies the dominant power consumer in future cellular networks, the Long Term Evolution (LTE) radio Base Station (BS), and proposes mechanisms that enhance the BS energy efficiency by reducing its power consumption under target rate constraints. These mechanisms trade spare capacity for power saving. First, the thesis describes how much power individual components of a BS consume and what parameters affect this consumption based on third party experimental data. These individual models are joined into a component power model for an entire BS. The component model is an essential step in analysis but is too complex for many applications. It is therefore abstracted into a much simpler parameterized model to reduce its complexity. The parameterized model is further simplified into an affine model which can be applied in power minimization. Second, Power Control (PC) and Discontinuous Transmission (DTX) are identified as promising power-saving Radio Resource Management (RRM) mechanisms and applied to multi-user downlink transmission. PC reduces the power consumption of the Power Amplifier (PA) and is found to be most effective at high traffic loads. DTX mostly reduces the power consumption of the Baseband (BB) unit while interrupting transmission and is better applied in low traffic loads. Joint optimization of these two techniques is found to enable additional power-saving at medium traffic loads and to be a convex problem which can be solved efficiently. The convex problem is extended to provide a comprehensive power-saving Orthogonal Frequency Division Multiple Access (OFDMA) frame resource scheduler. The proposed scheduler is shown to reduce power consumption by 25-40% in computer simulations, depending on the traffic load. Finally, the thesis investigates the influence of interference on power consumption in a network of multiple power-saving BSs. It discusses three popular alternative distributed uncoordinated methods which align DTX mode between neighbouring BSs. To address drawbacks of these three, a fourth memory-based DTX alignment method is proposed. It decreases power consumption by up to 40% and retransmission probability by around 20%, depending on the traffic load.

With each technology generation we get more transistors per chip. Whilst processor frequencies have increased over the past few decades, memory speeds have not kept pace. Therefore, more and more transistors are devoted to on-chip caches to reduce latency to data and help achieve high performance. On-chip caches consume a significant fraction of the processor energy budget but need to deliver high performance. Therefore cache resources should be optimized to meet the requirements of the running applications. Fixed configuration caches are designed to deliver low average memory access times across a wide range of potential applications. However, this can lead to excessive energy consumption for applications that do not require the full capacity or associativity of the cache at all times. Furthermore, in systems where the clock period is constrained by the access times of level-1 caches, the clock frequency for all applications is effectively limited by the cache requirements of the most demanding phase within the most demanding application. This motivates the need for dynamic adaptation of cache configurations in order to optimize performance while minimizing energy consumption, on a per-application basis. First, this thesis proposes an energy-efficient cache architecture for a single core system, along with a run-time support framework for dynamic adaptation of cache size and associativity through the use of machine learning. The machine learning model, which is trained offline, profiles the application’s cache usage and then reconfigures the cache according to the program’s requirement. The proposed cache architecture has, on average, 18% better energy-delay product than the prior state-of-the-art cache architectures proposed in the literature. Next, this thesis proposes cooperative partitioning, an energy-efficient cache partitioning scheme for multi-core systems that share the Last Level Cache (LLC), with a core to LLC cache way ratio of 1:4. The proposed cache partitioning scheme uses small auxiliary tags to capture each core’s cache requirements, and partitions the LLC according to the individual cores cache requirement. The proposed partitioning uses a way-aligned scheme that helps in the reduction of both dynamic and static energy. This scheme, on an average offers 70% and 30% reduction in dynamic and static energy respectively, while maintaining high performance on par with state-of-the-art cache partitioning schemes. Finally, when Last Level Cache (LLC) ways are equal to or less than the number of cores present in many-core systems, cooperative partitioning cannot be used for partitioning the LLC. This thesis proposes a region aware cache partitioning scheme as an energy-efficient approach for many core systems that share the LLC, with a core to LLC way ratio of 1:2 and 1:1. The proposed partitioning, on an average offers 68% and 33% reduction in dynamic and static energy respectively, while again maintaining high performance on par with state-of-the-art LLC cache management techniques.

Energy consumption has become a major research topic from both environmental and economical perspectives. The telecommunications industry is currently responsible for 0.7% of the total global carbon emissions, a figure which is increasing at rapid rate. By 2020, it is desired that CO2 emissions can be reduced by 50%. Thus, reducing the energy consumption in order to lower carbon emissions and operational expenses has become a major design constraint for future communication systems. Therefore, in this thesis energy efficient resource allocation methods have been studied taking the Long Term Evolution (LTE) standard as an example. Firstly, a theoretical analysis, that shows how improvements in energy efficiency can directly be related with improvements in fairness, is provided using a Shannon theory analysis. The traditional uplink power control challenge is re-evaluated and investigated from the view point of interference mitigation rather than power minimization. Thus, a low complexity distributed resource allocation scheme for reducing the uplink co-channel interference (CCI) is presented. Improvements in energy efficiency are obtained by controlling the level of CCI affecting vulnerable mobile stations (MSs). This is done with a combined scheduler and a two layer power allocation scheme, which is based on non-cooperative game theory. Simulation results show that the proposed low complexity method provides similar performance in terms of fairness and energy efficiency when compared to a centralized signal interference noise ratio balancing scheme. Apart from using interference management techniques, by using efficiently the spare resources in the system such as bandwidth and available infrastructure, the energy expenditure in wireless networks can also be reduced. For example, during low network load periods spare resource blocks (RBs) can be allocated to mobile users for transmission in the uplink. Thereby, the user rate demands are split among its allocated RBs in order to transmit in each of them by using a simpler and more energy efficient modulation scheme. In addition, virtual Multiple-input Multiple-output (MIMO) coalitions can be formed by allowing single antenna MSs and available relay stations to cooperate between each other to obtain power savings by implementing the concepts of spatial multiplexing and spatial diversity. Resource block allocation and virtual MIMO coalition formation are modeled by a game theoretic approach derived from two different concepts of stable marriage with incomplete lists (SMI) and the college admission framework (CAF) respectively. These distributed approaches focus on optimizing the overall consumed power of the single antenna devices rather than on the transmitted power. Moreover, it is shown that when overall power consumption is optimized the energy efficiency of the users experiencing good propagation conditions in the uplink is not always improved by transmitting in more than one RB or by forming a virtual MIMO link. Finally, it is shown that the proposed distributed schemes achieve a similar performance in bits per Joule when compared to much more complex centralized resource allocation methods.

Energieffektiviseringar är ett verktyg för att minska energianvändningen och de miljöbelastningar den ger upphov till, men de miljömässiga vinsterna av effektiviseringar äts i många fall upp av s.k. rekyleffekter (RE). Den här studien handlar om hur dessa rekyleffekter kan förebyggas vilket skapar möjligheter för mer miljömässigt hållbara energieffektiviseringar. Arbetet första frågeställning syftade till att ge svar på om direkta RE uppstått i samband med energieffektiviseringar som gällde belysning inom företag. Om inga direkta RE av betydelse uppstått innebär det att de besparingar som gjorts blivit tillgängliga för investeringar i andra typer av konsumtion av varor och tjänster. Dessa varor och tjänster är i sin tur miljöbelastande, vilket ger upphov till s.k. indirekta RE. Arbetets andra frågeställning syftade därför till att ge svar på vad som skulle motivera företag att satsa dessa resurser på miljöförbättrande åtgärder för att dämpa dessa indirekta RE. Beräkningen av direkt RE gjordes med en "före- och efteranalys" av energianvändningen i samband med energieffektiviseringen. För att isolera vad som var direkt RE samlades också data in kring faktorer som påverkar energianvändningen som förändringar av upplyst golvyta och ljusstyrka samt installation av belysningsstyrning. För att besvara arbetets andra frågeställning gjordes en web-enkät. Studien kom att omfatta sex företag inom tillverkningsindustrin och detaljhandeln. Resultatet av beräkningen av direkt RE visar på resultat mellan 4,7 % till -72,2 % vilket innebär att ekonomiska besparingar gjorts. Resultatet visade att besparingarna i första hand användes till att förbättra företagens resultat och produktion. Företagen såg inga hinder i att investera dessa resurser i miljöförbättrande åtgärder, men dessa investeringar gjordes sällan. Faktorer med starka drivkrafter för att motivera sådana investeringar identifierades som lösningar med potential att stärkta företagens varumärke, med en tydlig koppling till företagens verksamhetsområde och miljöpolicy. Möjligheten till att få råd och utbildning för att förbättra företagens miljöprestanda var också en stark drivkraft. / Improving energy efficiency is a way to reduce energy use and the environmental strain the latter can cause, but the environmental gains of such measures are in many cases diminished by rebound effects (RE). This study is an examination of how these RE can be prevented, thereby creating opportunities for more environmentally sustainable energy efficiency improvements. The first part of this study was aimed at determining if direct RE have emerged in parallel with increased energy efficiency efforts of indoor lighting within corporations. If no direct RE of significance could be measured, the cost savings that have occurred would then be available for investment in other types of goods and services. These goods and services, in turn represent a strain on the environment, giving rise to so-called indirect RE. The second part of this study was therefore aimed at determining what would motivate corporations to invest these cost savings in environmental improvement measures to lower those indirect RE. The calculation of direct RE was done with a “before-after” analysis of energy use in connection with energy efficiency improvement. In order to isolate the direct RE, data was also gathered about factors that effect energy use, such as changes in illuminated floor area and luminosity as well as installations of automated lighting control systems. A web survey was used for the second part of this analysis. Six companies within the manufacturing and retail industries participated in this study. The calculation of direct RE yielded a result between 4.7% to -72.2%, which showed that cost savings had been made. The results also indicated that the savings were primarily used to increase the companies’ profit margins and production. The companies did not see any obstacles to invest these resources in environmental improvement measures, but these investments were rarely made. The factors identified as strong motivators for such investments were solutions with the potential to improve the companies’ brand, with a clear connection to their trade and environmental policy. The possibility to get guidance and education on how to improve environmental performance was also a strong motivator.

Independent metering poses a possibility to improve energy efficiency of throttlecontrolled hydraulic single-rod cylinder drives. This paper deals with energetic potentials gained through variable circuitry that come along with independent metering. A method to assess energetic potentials is described, based on load specific, optimal operating modes. As a means of yielding maximum energy efficiency for a wide range of applications, a smooth mode switching algorithm that minimizes losses and allows good motion tracking is proposed. The mode switching algorithm is validated in simulation and on a test stand.

Pneumatic linear drives are widely used in manufacturing, mainly for handling tasks. Due to rising interest in environmental matters and increasing energy costs, energy efficiency has become a major issue in industrial applications. There is a growing competition between pneumatic and electromechanical drives. Pneumatic drives are said to have a lower efficiency while the initial costs of electromechanical drives are higher. The operating costs of electromechanical as well as pneumatic drives are induced by their exergy efficiency. The efficiency of the drives depends on parameters like cycle time, load applied to the cylinder and its acceleration and velocity. Former research did only provide limited data on the influence of these parameters. The paper provides an overview on the exergy efficiency of pneumatic and electromechanical drives and its dependency on the mentioned parameters. Since electromechanical drives are often used to replace pneumatic drives both technologies are examined in typical applications for pneumatic drives, including horizontal and vertical movement and sustaining a load for different periods in vertical usage.

The objective of this thesis is to model and analyze the energy consumption in heterogeneous cellular systems and develop techniques to minimize it. First, the energy consumption is modeled and analyzed for multi-layered heterogeneous wireless systems. This work encompasses the characterization of all the energy consumed at the base stations. Then, a novel on-off and cell-association scheme is proposed to minimize the overall network energy consumption while satisfying the spatially- and temporally-varying traffic demands. Second, we exploit the use of multi-stream carrier aggregation not only to improve the energy efficiency, but also to balance it with the conflicting objective of capacity maximization. Third, we analyze the performance of discontinuous reception methods for energy savings within the user equipments. Then, for scenarios that support carrier aggregation, we develop a cross-carrier-aware technique that further enhances such savings with minimum impact on the packet delay. Fourth, the use of small cells as an energy-saving tool and its limitations are analyzed and modeled in OPNET, a high-fidelity simulation and development platform. To bypass such limitations, a novel small cell solution is proposed, modeled, and analyzed in OPNET and then compared against its existing alternative.